When I uses chat gpt it says the Mobil 1 0w40 HTHS is 3.7, the Castrol is 3.7 and the motul 5w40 is 3.8. But when I pull up the data sheets for the mobile 1 and Castrol, it doesn't actually say on them.
Since we are going into winter soon, im tempted to just grab the mobile 1 0w40 which is on sale for 36 CAD (25 usd) a jug. Just run it up until summer comes around and revisit the discussion with either a motul, ravenol, HPL or even a 50 weight. I'll probably only put 3k miles on the oil until then.
And here I thought this thread would make things more clear and easy. I'm more unclear than ever lol.